Pea aphids harboring Hamiltonella defensa bacteria that are infected with the APSE virus tend to be spared from death due to a normally deadly parasitic wasp (Aphidius ervi), according a recent research report. Typically, the wasp lays its eggs in the aphid and the wasp larvae consume the aphid from the inside out. The APSE virus produces toxins that appear to be involved in the anti-wasp defense. The researchers first showed that pea aphids without the H. defensa bacteria were highly vulnerable to the parasitic wasp, while pea aphids with the H. defensa bacteria tended to be resistant. The scientists then showed that pea aphids carrying H. defensa bacteria that had lost the APSE virus were also vulnerable to parasitic wasp attack. On the other hand, pea aphids carrying APSE-infected H. defensa were resistant. The research is the first to demonstrate that a virus that infects bacteria can help, rather than harm, the bacteria's animal host, said first author Dr. Kerry Oliver. This work was reported in the April 21 issue of Science. The accompanying photo is credited to Dr. Oliver. [Press release] [Science abstract]